Capillary action, or capillarity, is the ability of a liquid to flow against gravity where liquid spontaneously rises in a narrow space such as between the hairs of a paint-brush, in a thin tube, in porous material such as paper, in some non-porous materials such as liquified carbon fiber, or in a cell. This effect can cause liquids to flow against the force of gravity, sun or any electro magnetic field affecting fluid flow. It occurs because of inter-molecular attractive forces between the transporting liquid and surrounding surface having a different surface energy. For the case of a tube, if the diameter of the tube is sufficiently small, then the combination of surface energy (which is caused by cohesion within the liquid) and force of adhesion between the liquid and tube wall act to lift the liquid.
While there are numerous methods for liquid transport based on capillary action, there is still a need for improved microcapillary films and/or foams suitable for capillary action fluid transport.